S36 AN ACCOUNT OF THE 
as Aszimuths ave far from the precision of 3 or 4 it would be a loss of 
time attending to this correction. 
Ir is thus then that the differences of latitude, longitude and Azimuth 
-are found; the calculations are short and symmetrical, and the employment 
of ‘the several tables are a good assurance against errors accumulating too 
much. The figure of the earth is fully attended to, and yet the whole 
operation is shorter, simpler and less liable to oversight, than even the very 
erroneous, though common method called Mrrcator’s. Having shewn 
the principles, on which the following results have been obiaimed, we may 
now proceed to the details of the calculation. 
Tue latitude of the Belville and Chir stations have been stated at 
29 5% 10 and 30 50 18, the difference bemg 53 8. The Azimuth was 
found to be 3 25 05 N. W. Itis proposed to determine their distance, 
regard being had to the figure of the earth. 
C ~ 
Let C be the place of the Chir’ station, and B that of 
Belville, L C being the difference of latitude, and C B 
the distance. Draw the perpendicular to the meridian pp B. 
Pul’=CBr=p Be=Cp,andpL—«2,Z2 0B L= 
fe EB Azimuth — Z. 
By spherl. Trig. 1. Tang. ? Cos. Z=tang. #, or 3 f Cos. as dl ad L+ 3 wf 
Divdg. by Cos. Z.* 2. ee ee 
Cos. Cos. %. 
Article 9. 3. Buta*® == 4? Tang. b 
27. 
* f, is neglected here as too smali to affect the value of <. 
